So we're now going to look at some of the options that network operators or endsites have for multihoming. And first off we're going to look at what a transit provider is and what they do. A transit provider is another autonomous system which is used to provide the local network with access to other networks. They might provide just local transit. They might provide regional transit, but is most common today they are usually providing transit to the whole internet. And transit providers need to be chosen wisely it's not a case of just going out there finding the cheapest or most accessible one if you have only one transit provider you have no redundancy we're back to the whole purpose of this presentation we're trying to do multihoming so that we have redundancy if you have too many transit providers it becomes really hard if not impossible to balance traffic on the multitude of external links and there's no economy of scale it costs a lot more per megabit per second internet transit capacity gets cheaper with the greater amounts of bandwidth that is purchased and because of all this it becomes really hard to provide any service quality to the end-users the general recommendation and again considered best practice by many operators today is to have at least two transit providers but preferably no more than three two transit providers is the simple option 1 provides redundancy in case the other one has a problem 3 at least gives a little bit more variety again depending where the network operator is located globally common mistakes that people make includes signing up with too many transit providers because they then end up with lots of small circuits which cost more per megabit per second equivalent larger ones transit rates per megabit per second reduce with increasing transit bandwidth purchased and becomes really hard to implement any type of reliable traffic engineering that doesn't need daily fine-tuning depending on customer activities and even with signing up with two or three transit providers another common mistake is that there's no diversity because the chosen transit providers are all reached over the same submarine cable or over the same satellite connection or even if the chosen transit provide us at good connectivity between the local network and the transits may be there onward connectivity is either poor as far as transit goes or they have very very poor peering arrangements so when a network operators trying to choose how to multi-home who the purchased transit from is vitally important it is not the cheapest answer to an RFP peers on the other hand are another autonomous system with which the local network has agreed to exchange locally sourced routes and traffic now these can be a private pier which is a private link between two providers for the purpose of interconnecting or there can be a public pier for example at an internet exchange point where network operators meet and freely decide who they will interconnect with industry recommendation for many years has been pierre as much as possible and again the many mistakes made on the peering site mistaking at transit providers exchange business for a no-cost open neutral public peering point some operators have cashed in in the good name of internet exchange points and called the for-profit transit business an exchange they're exchanging packets they're exchanging traffic that does not make them a neutral no-cost public peering point another mistake is not working as hard as possible to get peering I have seen over the years many network operators will turn up in the same building same data center as an internet exchange point is located in yet they don't interconnect there they don't peer they don't connect to the exchange point fabric and try and peer with other operators there some people have said that transit is sometimes cheaper than peering that's quite rare given the cost of connecting to an exchange point is little more than the annual membership fee and another common mistake is ignoring or avoiding competitors simply because the competition even though the competitor is potentially a really viable peering partner do you give customers of the local network as well as the competitor a better experience after all operators are here to ensure the best end-user experience for their own customers and if content is hosted in a competitor's Network surely interconnecting would be the best thing to do competitors normally fear that they would lose customers hosted content to the competition but actually the opposite is true interconnecting to service providers serving the same locale usually means a net benefit for both network operators.

© Produced by Philip Smith and the Network Startup Resource Center, through the University of Oregon.

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